The present invention relates to a method of forming a circuit board and, more specifically, to a method of forming a circuit board including wiring with conductive vias.
Interposers with fine wiring are required in three-dimensional chip stacking and so-called 2.5-dimensional packages. An interposer establishes an electrical connection (relay) between mounted IC chips and between an IC chip and a wiring board. An interposer requires a wiring thickness that is not much thinner than the current thickness from the perspective of electrical characteristics. In other words, wiring with a high aspect ratio is required.